How to create a spiral block in blender
Start with a single edge from the center to the side.



Add a screw modifier with a positive screw value.



Fill F the created n-gon (1) and add a triangle (2), connecting the first point and the last segment.



Select the border edge loop &#9095; Alt RMB and extrude it downwards E > Z  LMB. Scale the extruded edgeloop to 0 along the Z-axis. SZ0
I added an edge split modifier to sharp the sharp edges.